MC68HC05P18 Datasheet, PDF (66/144 Pages) Freescale Semiconductor, Inc – Advance Information

Freescale Semiconductor, Inc.
Input/Output (I/O) Ports
7.5 Port C
Port C is an 8-bit bidirectional port which can share pins PC3–PC7 with
the A/D subsystem. The port C data register is located at address $0002
and its data direction register (DDR) is located at address $0006. Reset
does not affect the data registers, but clears the DDRs, thereby setting
all of the port pins to input mode. Writing a logic 1 to a DDR bit sets the
corresponding port pin to output mode (see Figure 7-3). Two port C
pins, PC0 and PC1, can source and sink a higher current than a typical
I/O pin. See Section 13. Electrical Specifications regarding current
specifications.
Port C may be used for general I/O applications when the A/D
subsystem is disabled. The ADON bit in register ADSC is used to
enable/disable the A/D subsystem. Care must be exercised when using
pins PC0–PC2 while the A/D subsystem is enabled. Accidental changes
to bits that affect pins PC3–PC7 in the data or DDR registers will produce
unpredictable results in the A/D subsystem. See Section 9.
Analog-to-Digital (A/D) Converter.
READ $0006
WRITE $0006
RESET
WRITE $0002 ^(RST)
READ $0002
INTERNAL
HC05
DATA BUS
DATA DIRECTION
REGISTER BIT
DATA
REGISTER BIT
HIGH CURRENT
CAPABILITY, PC0
AND PC1 ONLY
OUTPUT
I/O
PIN
Figure 7-3. Port C I/O Circuitry
Advance Information
66
MC68HC(8)05P18 — Rev. 2.0
Input/Output (I/O) Ports
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